Plastic cylinder heater coil and method of making same



May 9, 1950 PLASTIC CYLINDER HEATER COIL AND METHOD 0F MAKING SAME R G.BOYDSTUN Filed Oct. 27, 1947 INVENTOR.

ATTE! RN EYB atented May 9%,

OFFIC PLASTIC CYLINDER HEATER COIL AND' METHOD OF MAKING SAME Robert G.Boydstun, Fort Worth, Tex.

Application October 27, 1947, Serial No. 782,319

This invention relates tocoil heaters for flow lines, pipes and tubingwhere it is desired to maintain temperatures above the temperature ofthe atmosphere in products passing therethrough, and Ain particular acylindrical plastic heater coil and the method of making the samewherein a pipe is wrapped with paper, a coating of plastic material isplaced around the paper and baked until it hardens, then a coil of wireis placed on the plastic, and another coating of plastic material isplaced over the wire and baked. Metal rings may be cast into the plasticat the ends to form terminals.

The purpose of this invention is to provide a preformed thermogenicplastic element adapted to be placed around pipes, tubing, and the liketo provide constant temperatures therein and eliminate winding of pipeand tube joints.

Various methods have been employed for applying heat to piping, tubingand the like, particularly by covering the pipe and joints thereof withasbestos and Wrapping the asbestos with thermo-electric Wire, but theseform an integral part of the pipe and when it is desired to replace thepipe a new unit is required. With this thought in mind this inventioncontemplates preformed plastic units with copper or aluminum magnet wirecoils therein that may readily be placed over and removed from the pipeor tube and particularly tubing with upset ends.

The object of the invention is to provide a method of making preformedthermogenic plastic cylinders that may readily be placed on and removedfrom pipe, tubing, and the like.

Another object of the invention is to provide a method of making plasticcylinder heater coils wherein the coils may be made for piping and tubesof different sizes.

Another object of the invention is to provide preformed plastic heatercoils in which permanent contacts are provided around the ends.

Another object of the invention is to provide preformed plastic heatercoils that may be placed end to end on pipe or tubing and in which thecoils will make contact through the ends thereof.

A further object of the invention is to lprovide a method of makingthermogenic plastic cylinders for use on pipe, tubing and the like inwhich the cylinders are of simple and economical construction.

With these and other objects and advantages in view the inventionconsists in the new and useful combination, construction, andarrangement of parts as more fully described herein, set

aciaims. (ci. 21e-39) closed in the accompanying drawings forming parthereof, wherein:

Figure l is an elevational view showing a single cylindrical heater uniton a pipe.

, Figure 2 is a longitudinal section through the unit taken on line 2-2of Figure 1.

Figure 3 is a view illustrating a plurality of units on a tube with anupset end with the outer plastic coating of one of the units brokenaway.

Figure 4 is a cross section through a tube taken on line ll-Li of Figure3 showing an end elevation of the heater unit and illustrating shimsused between the unit and tube.

Referring now to the drawings wherein like reference characters indicate`corresponding parts the plastic cylinder heating coil of this inventionincludes an inner plastic layer Ill, a wire coil il, and outer plasticlayer I2, and rings I3 and I4 at the ends.

The units are formed by Wrapping a pipe or tube I5 with brown paper I6,or the like, applying the inner layer I0 of plastic over the paper,baking the layer of plastic -until hard, wrapping the layer of plasticwith the wire coil Ii, and

' then applying the outer plastic layer I2 and baking the outer layeruntil it hardens. The paper core may then be washed out. The ends of thewire coil may be connected to the rings I3 and I4 and the rings may becast into the plastic.

The thermogenic plastic uints are manufactured as illustrated in Figure2 with the layer of paper between the inner plastic layer or cylinderand when the units are installed on a pipe or tube thin arcuate shirnsI'I may be inserted in the ends as shown in Figure 4 to space the innersurfaces of the -units uniformly from the pipe or tube.

It will be understood that any suitable plastic may be used for theinner and outer layers although it is preferred to use Dow Chemicalplastic or a similar material. It will also be understood that anysuitable thermo-electric Wire may be used and the 'wire may be ofdifferent sizes for different conditions.

The plastic cylinders have been described as formed of one coating orlayer and it will be understood that both the inner and outer plasticlayers may consist of a plurality of layers. The rings at the ends ofthe units form contacts when the units are positioned end to end and itwill be understood that any suitable means may be provided forconnecting the coils of the units.

t will also be understood that other changes forth in the claimsappended hereto, and dismay be made in the design and arrangement of 3parts without departing from the spirit ,of the invention.

What is claimed is:

1. In a cylindrical electric heater, the combination which comprises aninner cylindrical sleeve of insulating plastic material, athermoelectric Wire coil positioned around said sleeve, an outerinsulating plastic sleeve covering and providing an enclosure for saidWire coil and in which said coil isembedded, and annular contact ringspositioned at the ends of said plastic sleeves and connected to the endsof said Wire coil, said rings providing contact means vfor completing acircuit through the thermo-electricrvvirefoil of the heaterandpositioned toY contact corresponding rings of similar heaters with aplurality of said heaters removably mounted on a pipe or .Y

the like. y Y

2. In a cylindrical electric heater, the combination which comprises aninner cylindrical sleeve of insulating plastic material, a thermo.-electric wire Vcoil positioned around Said sleeve,

' Y an ,outer insulating plastic sleeve coveringand providing anenclosure for said Wire coil and which said coil is embedded,.annulancontact rings positioned at the .endsof said plastic sleevesends thereof. ROBERT G. BOYDSTUN.

REFERENCES CITED The following references are of record in the ille Qf.this patent: v

v unrTEnsTATEs PATENTS Number Name Date 8,584 Parry et al July 4, 1865806,039 Williamson et al. Nov. 28, 1905 `l..23.2;36L-'.l.`.;r1,1.,l1ritrl .et 1,-; .July 19,1917 .1.309521 rinkem of Jill?15e v19.19 1,315,084 cox en. 19,. 1.92.1 :13.18406 June 18, 19291,767,586 June `24. 1.939 Alle is, 1949

